How to select welded elements with marked seams
When you use the Linked select, on the (T) toolbar popup you can choose what kind of link you want to use.



If this menu is collapsed there is a + tab that can open it back up on the bottom of the toolbar.

Blender usually automatically sets it to the Seam selection once you've unwrapped your object, but you can [shift]+[click] any of the options to turn them on and off. (If you know programming, this is an AND function; it will only select something that fulfills all of those selections.)